1. Field of the Invention
The present invention relates to plural developers or toners each of which contains different materials, an image-forming method by use of them and an image-forming system therefor.
Particularly, it relates to monocolor toners each of which contains different coloring agents, developers comprising these toners, a color-image forming method for forming color images by use of these toners or developers and a color image-forming system therefor.
2. Description of the Prior Art
Recently, as information for an office and a person are increasing, color copy is sought in the electrophotographic field.
For example, sought are electrophotographic copying machine which can form exact full-color images from a manuscript, or copying machines, printers, facsimiles and the like of digital or analog type having multicolor function, business-color function and the like in order to provide such color images from the necessary parts as demanded by the operator.
In these image-forming systems, a visible image is formed by electrophotography by use of plural monocolor developers or monocolor toners. Such developers and toners comprise for optimization of their performance various additives e.g. charge controlling agents (various dyes, metal complexes, etc.), magnetic powders and fluidity improvers (various oxides, nitrides, etc.). It goes without saying that in forming multi-color images, these developers or toners contain different coloring agents respectively or they are constituted of different binder resins respectively.
When plural of toners or developers containing various materials are utilized in an image-forming process, optimal image-forming conditions are different from one toner or developer to the other, giving rise to troubles such as difficulty in control and unstable picture quality and so on. Further, variation in their image-forming performance under environmental fluctuation differs from one toner or developer to the other, resulting in image instability under varying environmental conditions, even after their performance is adjusted under a definite environment. Or even under identical environmental conditions, different corrections are required between individual toners or developers in the course of their continuous use because of the difference in durability from one toner or developer to the other.
Recently known is a technique in which plural coloring agents are contained in a developer or toner. This developer or toner has difficulty to control because of different electrification performance from one coloring agent to the other or gives unstable picture quality. Such a trouble widely occurs notably in image-forming methods making use of plural/single toner(s) or developer(s) containing various coloring agents and the system used therefor. Even if a coloring agent is used in common, the other materials contained therein are different and the above trouble is brought about. When developers or toners containing a coloring agent in common are utilized in one system, the same trouble arises. For example, in the case of micro-reader/printer which makes use of 2 types of toners comprising a common coloring agent, charge controlling agents differs in electrification polarity for normal and reversal development. This poses the trouble to be resolved.
Furthermore, when toners or developers containing various kind of materials are used in an image-forming process, the individual toners or developers undergo different variations from one to the other under different environmental conditions. When the variations in use are monitored, the individual toners or developers must be monitored. For example, when an image concentration is detected automatically in forming full color images (this system is referred to as AIDC), it becomes necessary to make detection for each toner of yellow, cyan, magenta and black. This leads not only to difficulty in control but rises in cost.